Among registered Ohio voters who identify as Republicans, Moreno’s image is a bit more favorable than the other candidates among voters that identify as “strong Republicans,” but weaker among “not very strong Republicans.” In a SurveyUSA/Ohio Northern University poll published last week, voters were asked if they had a favorable or unfavorable opinion of various politicians. Among strong Republicans, Moreno had net +26 favorability, while LaRose and Dolan were each at net +20 percent favorability. Among not very strong Republicans, Dolan was in the lead with net +12 favorability, compared to LaRose at +9 and Moreno at +5.

—Mary Radcliffe, 538

Democrats (and allied independents) currently hold a bare majority in the U.S. Senate, with 51 seats to Republicans’ 49. But control of the chamber is at stake in November, and the Senate race in Ohio is one of a few competitive contests that could decide control of the chamber.

Three Republican contenders are facing off today for a chance to challenge incumbent Democrat Sherrod Brown in that contest: Matt Dolan, a state legislator running with the endorsement of former Ohio Sen. Rob Portman; Frank LaRose, the current Ohio Secretary of State running on a campaign of conservatism and electability; and Bernie Moreno, a businessman with endorsements from Trump, a dozen members of Congress including Ohio Sen. J.D. Vance and the Club for Growth PAC, one of the oldest conservative PACs in the country.

Moreno, who appeared alongside Trump in several campaign events this past weekend, has gained significant ground in the polls since the former president endorsed him in mid-December. Then, he was polling at 16 percent in 538’s polling average — and now he’s hovering in the mid- to-high-20s. Democrats view Moreno as the weakest candidate for the general election and last week began airing a television ad intended to boost his standing by “attacking” his conservative record and support for Trump ahead of Tuesday's primary.

But the polls show a tied race between Dolan and Moreno, who each lead LaRose by 10 percentage points. That’s too close for polls to provide a reliable signal of who is decisively leading: Per our database of historical polls, surveys of Senate primaries miss the margin between the winner and runner-up by 6.5 points on average.

Looking ahead to the general election, the winner of today’s Republican primary matters not just in deciding who might be Ohio’s next senator, but in deciding control of the Senate come 2025. Since West Virginia Democratic Sen. Joe Manchin decided to retire, prognosticators largely expect the Republicans to pick up at least one seat this November. That means Democrats and Republicans start their fight for the majority from a 50-50 tie, and Democrats need to at least hold on to the rest of their endangered seats — and for Biden to win — to maintain control.

Ohio is a red state, but Brown has managed to run ahead of expectations in previous cycles. So has fellow endangered Democrat, Montana Sen. Jon Tester. But neither of them have run in a presidential cycle since 2012, when President Barack Obama pulled off a surprising reelection and Democrats gained two seats in the Senate. Brown will face not just the strength of his opponent in November, but the partisanship of his constituents. The Cook Political Report rates the Ohio Senate race a toss-up.

—G. Elliott Morris, 538

The general election campaign has only just begun, and already the presidential candidates are trying to crowd us out of the polling analysis business. At a recent campaign stop, Biden suggested the polls showing him losing to Trump nationally and in all the major battleground states may not be accurate because it takes “six zillion calls to get one person on their cell phone.”

In the latest installment of the 538 Politics podcast we assess whether Biden has a point and what we should make of general election polls seven and a half months out from voting. We also look back at a viral YouGov poll that showed 20 percent of young Americans believe the Holocaust is a myth. It turned out to likely be entirely bogus. Plus, we tackle the main event of the evening — the Republican Senate race in Ohio.

If you want to take a listen while we wait for results to come in, smash the play button below!

—Galen Druke, 538

Former President Donald Trump and President Joe Biden have both clinched their respective nominations in the presidential race, but primary season is just getting started. The biggest state to watch tonight is in Ohio, where a closely contested GOP primary will decide which Republican faces off against Sen. Sherrod Brown in one of this fall’s biggest Senate races. Trump-endorsed businessman Bernie Moreno seems to have an edge in that contest over state Sen. Matt Dolan and Ohio Secretary of State Frank LaRose. Trump-aligned Republicans will be pulling for Moreno today — but so might Democrats, who see Moreno as an easier target to defeat in November.

Which wing of the GOP comes out ahead seems to be the theme of the day throughout the Buckeye State, where we’re also tracking a slew of competitive Republican primaries for U.S. House. Meanwhile, two incumbents in Illinois — Democratic Rep. Danny Davis and Republican Rep. Mike Bost — are looking to stave off tough primary challenges, while California will host a Super Tuesday rematch in a special election to decide who will fill former Speaker Kevin McCarthy’s seat in the House for the remainder of this year.

As for timing, we should start to see results come in shortly after polls close at 7:30 p.m. Eastern in Ohio and 8 p.m. Eastern in Illinois. As always, 538 analysts will be here bringing you the latest results and analysis throughout the evening. Thanks for joining us!

—Tia Yang, 538

Merrin, the last-minute addition to the race, is projected to win the primary in Ohio's 9th District, according to ABC News. He will face incumbent Kaptor. Despite her incumbency, the seat could be tough for the long-serving Democrat to hold onto. As Nathaniel wrote earlier, Republicans in the state redrew the district to make it more Republican. But finding the right candidate has been tough for them: They'll be holding out hope that Merrin, who's been involved in his own intraparty battles in the state, will win this November.

—Monica Potts, 538